In recent years, various information processing devices have been provided with a display section, such as an LCD (Liquid Crystal Displays), for displaying its operation status and processing information. As the display section, a display touch panel having a display screen, such as LCD, and a touch panel placed thereon is adopted in many cases. Such a display touch panel displays keys (buttons, icons, or the like) for accepting user's instructions on a display screen, detects a position in the display screen where the user touches (contacting instruction) or a position in the display screen to which the user locally brings his/her finger or the like closer (locally approaching) (non-contacting instruction), and find out which key for inputting instruction is used by the user on the basis of the position thus detected and a display position of the key.
The above-described keys provided on the display screen are sometimes called “soft keys”, as distinguished from keys as hardware provided on a keyboard. However, in the present application, the above-described keys are simply called “keys”.
For example, in the case of a multiple function printer (MFP) having a plurality of functions as copying machine, printer, scanner, and others and a function of communicating with other information processing device, a display screen for selection of copy styles based on a single-sided printing document and a double-sided printing document in copy mode shows the following four keys: “1-sided original, 1-sided copy”, “l-sided original, 2-sided copy”, “2-sided original, 2-sided copy”, and “2-sided original, 1-sided copy”. In addition, the display screen shows, for settings of trays holding recording sheets of different sizes, keys for selection of types of recording sheets (white papers, colored papers, OHP sheets, and others) and keys for selection of sheet sizes including “B5”, “A4”, “B4”, and “A3” sizes.
All of the keys are provided at fixed positions on the display screen. In many cases, keys available for a used operation are displayed in a normal state, but keys unavailable (invalid) for that operation are not displayed at all or displayed with low contrast to distinguish from the available (valid) keys. For example, if the multiple function printer does not have, as an option, a paper reversing device for double-sided printing, the two keys “1-sided original, 2-sided copy” and “2-sided original, 2-sided copy” out of the above four keys becomes unavailable (invalid) and are displayed in a different manner from the other available (valid) keys. Such a display style is adopted in various devices, not limited to the multiple function printer.
Meanwhile, on a facsimile and/or e-mail destination selection screen, the number of keys to be displayed varies according to the number of destinations being registered. For this selection screen, often adopted display style is a display style such that the keys are placed in a given pattern of locations in the display screen regardless of the number of keys. An example of such a display style is as follows: the keys are placed beginning at the top of the display screen, and if the keys are too much in number to be displayed on one screen, a scroll is showed up in the screen.
When such keys are displayed in large numbers on the display screen, different keys placed closer to one another increase the possibility that the touch panel could misidentify user's selection. This occurs not only because on a contacting-type touch panel, for example, the user tends to mistakenly touch a key, but also because the user's finger tends to touch two adjacent keys.
As the invention for preventing misidentification of the touch panel, patent document 1 (Japanese Laid-Open Patent Application No. 1999/003440 (Tokukaihei 11-003440; published on Jan. 6, 1999)) discloses a touch panel-type ticket vending machine having an infrared or ultrasonic touch panel, wherein a detection region in a display area of each fare button is made small, and a perimeter of the display area is a non-detection region. This arrangement makes it impossible to detect a light touch of the user's finger on the display area of the fare button, thus preventing an erroneous entry.
Patent document 2 (Japanese Laid-Open Patent Application No. 2000/253288 (Tokukai 2000-253288; published on Sep. 14, 2000) discloses the invention in which (a) a liquid crystal display panel provided in an image picking-up device like a video camera and an electronic still camera has a touch panel, (b) a sensing region corresponding to a pictograph displayed in an outer frame around the liquid crystal display panel is set on the touch panel so as to be adjacent to the corresponding pictograph, and (c) an area of the sensing region is larger than a display area of the corresponding pictograph. According to the patent document 2, it is operationally preferable that this invention cause the image picking-up device to perform an operation corresponding to the pictograph upon user's touch of the sensing region adjacent to the pictograph.
Patent document 3 (Japanese Laid-Open Patent Application No. 2003/280782 (Tokukai 2003-280782; published on Oct. 2, 2003) discloses an operation key device wherein various keys are displayed on an operation panel of an electronic information processing apparatus, such as the multiple function printer, and according to usage frequency of the displayed keys, a key image of a key used at a high frequency is changed in size and shape in conjunction with its detection region. According to the patent document 3, this arrangement allows the user to easily find necessary keys and to perform key operation without operation error.
However, in many devices, available keys vary depending upon user selected operation, user's setting, the presence or absence of options, or the like, even when contents displayed on the operation screen that accepts user's instructions are the same or similar among the devices. In this case, unavailable keys are made disappear from the operation screen or grayed out to be inconspicuous, whereas available keys are placed at the same position as possible to prevent the user from being confused.
In the case of the ticket vending machine described in the patent document 1, some fare buttons whose indicated amounts fall within the range of an amount inserted into a slot usually become available for display in ascending order, whereas the other fare buttons become unavailable for display. Therefore, a less amount inserted into the slot increases invalid area, but the setting of making the detection region smaller than the display area of the fare button is not changed.
That is, a certain fare button is always placed at the same position on the screen and just switched back and forth between availability (valid) and unavailability (invalid) for display. Therefore, there is no change in spacing between the fare buttons. Thus, it is only considered to prevent erroneous detection of the fare buttons.
Accordingly, the invention of the patent document 1 cannot optimize an ease of touch on the fare button and prevention of erroneous detection depending upon the number of fare buttons displayed.
Further, in the invention of the patent document 2, pictographs shown in an outer frame around the liquid display panel are printed or engraved on its surface so as to be displayed at fixed positions, so that settings of the sensing regions corresponding to the respective pictographs are also fixed. Therefore, a design of the pictograph cannot be changed according to a content of user selected operation. Accordingly, it is impossible to change the sensing region in size according to a content of the operation for optimization of usability.
Still further, the invention of the patent document 3 merely discloses that a key used at a high frequency is changed in size or shape, with a key image being in conjunction with a detection region. That is, it is impossible to enhance operability by preventing erroneous detection in such a manner that a detection region of the available key is made larger so that detection is possible even with user's rough operation, when some keys become unavailable according to a content of the operation, and available keys are sparsely displayed on the screen, or conversely, the detection area is made smaller when the keys are densely displayed on the screen.
As described above, none of the above patent documents suggest that according to the operational status of the device, the detection region of the keys is changed in size with change in placement (key arrangement) of the keys, such as a position on the screen where the keys are displayed and the number of keys displayed on the screen.